1. Field of the Invention
The invention relates generally to containers having a plurality of component containers or compartments for containing a variety of dissimilar substances. More particularly, the invention relates to a dual compartment container for containing and isolating two separate substances and facilitating their mixture just before use by a consumer.
2. Description of the Prior Art
Dual compartment containers have been used in the past to ship and store products having component substances which must be kept separated until immediately prior to use. The separation may be necessitated for a variety of reasons. For example, separation may be necessary to extend the shelf life of a product because the component materials begin to degrade a short time after they have been mixed. Also, separation is necessary for products having component materials which create unacceptable or dangerous pressure within the container after they are mixed. In some situations, dual compartment containers are used merely to enable the mixing of the component materials within a common compartment and dispensing same from a common spout without the necessity of manually pouring the contents of one container into another container prior to use. This avoids spillage which, in addition to being unpleasant for consumers, may create a safety hazard if caustic substances are to be mixed. Spillage may also unacceptably change the ratio of the component materials required for producing a satisfactory product.
One example of a dual compartment common spout container is shown in U.S. Pat. No. 4,465,183. The dual oompartment container shown in this patent is intended for a hair ooloring product where each compartment contains a different liquid. Prior to use, a consumer would remove a breakable partition spacing the containers axially and screw the containers together thereby activating an internal knife member molded into one of the containers to cut foil membranes used to seal each container and keep their respective contents separated. There are several disadvantages associated with this container. For example, the knife member is integral with the top container and, therefore, requires fairly complex and costly molding operations. The lateral motion of the knife member relative to the membrane during the cutting action creates the possibility of tearing the membrane and, therefore, interfering with the mixing of the contents, especially if the component substances are somewhat viscous liquids. This container utilizes a separate piece (the breakable partition) which performs no other function than to maintain the containers separated during shipment and prior to use, thus also adding to the cost. Additionally, the container shown in this patent requires a three-step operation prior to use: (1) the user must remove the partition, (2) screw the containers together, and then (3) remove the cap sealing the spout. For customer convenience, a fewer number of operations would be preferable. This container requires two separate membrane seals, one for each separate compartment. One of these seals is an extra part, again adding to the cost of the overall container. Furthermore, the intermediate member which is used to hold and screw the containers together as they are being threaded toward each other is also an extra piece which adds to the complexity and cost of the device. The container disclosed in this patent also requires that the membranes sealing each of the containers be completely cut, thus possibly enabling the membranes to clog the spout of the container during use.
Another example of a dual compartment container is shown in U.S. Pat. No. 4,247,001. One of the compartments in this container has a flexible bottom wall and includes a cutting frame within its interior. Pressing the bottom wall in a given direction causes the cutting frame to press against a sealing membrane to cut it with a piercing action. One deficiency of this type of container is that the bottom wall must be protected during shipment to avoid premature piercing of the membrane. Another deficiency is that the container requires a separate cap or seal for the spout. This is an extra part adding to the cost and complexity of the container. Additionally, the operation of the container requires three steps: (1) the protective feature preventing premature motion of the flexible wall must be removed, (2) the flexible wall must be depressed to cut the membrane and (3) then the spout must be opened. In addition to the foregoing disadvantages, the containers shown in U.S. Pat. No. 4,247,001 are also not suitable for mixing viscous fluids. The presence of the knife frame within the container creates an impediment to material flow which interferes with complete mixing of such substances.
To overcome the disadvantages of the prior art, it is an object of this invention to provide a dual compartment container wherein only a single operation is required by the user to open the container and prepare the contents for use.
It is a further object of this invention to provide a dual compartment container for containing two separate substances wherein only one of the containers is sealed with a membrane.
It is still another object of this invention to provide a dual compartment container having an annular internal knife member for piercing a sealing membrane.
It is still another object of this invention to provide a dual compartment container having an annular internal knife member for piercing a sealing membrane without any relative lateral motion between the knife and the membrane.
It is yet another object of this invention to provide a dual compartment container having an annular internal knife member for piercing a sealing membrane as the cap of the container is being removed.
It is also a object of this invention to provide a dual compartment container that may perform its intended shipping, separating and mixing functions without the need for auxiliary spacing pieces to maintain separation of component parts prior to use.